Gaseous emissions from agricultural activities affect atmospheric composition, with significant consequences for air quality, climate, stratospheric ozone, and ecosystem health. FarmFlux is a NASA airborne mission to quantify U.S. agricultural emissions and trace their Earth system impacts. In late 2026 and 2027, FarmFlux will equip two aircraft with in situ gas and particle instrumentation and acquire observations over croplands and animal feeding operations throughout the Midwest and Western U.S. Analysis with advanced techniques (mass balance, eddy covariance) will provide near-direct quantification of actual emission and deposition fluxes that can be used to understand environmental drivers, improve model parameterizations, and enhance the utility of satellite retrievals. This presentation will detail the motivation, objectives, techniques, and expected outcomes of FarmFlux.